Protecting groups in polymers, photoresists and processes for microlithography

ABSTRACT

The invention relates to a photoresist composition having a protecting group and a protected material incorporated in a cyclic chemical structure. In this invention a protected material has a cyclic ether group or cyclic ester group as a protecting group. A specific example of a cyclic ether group is an alkylene oxide, such as an oxetane group, substituted with one or more fluorinated alkyl groups. A specific example of a cyclic ester is a lactone which may be substituted with methyl groups. The photoresist composition further includes a photoactive component. The photoresist composition of this invention has a high transparency to ultraviolet radiation, particularly at short wavelengths such as 193 nm and 157 nm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to photoimaging and, in particular, theuse of photoresists (positive-working and/or negative-working) forimaging in the production of semiconductor devices. The presentinvention also pertains to novel fluorine-containing polymercompositions having high UV transparency (particularly at shortwavelengths, e.g., 157 nm) which are useful as base resins inphotoresist and potentially in many other applications.

2. Description of Related Art

Polymer products are used as components of imaging and photosensitivesystems and particularly in photoimaging systems such as those describedin Introduction to Microlithography, Second Edition by L. F. Thompson,C. G. Willson, and M. J. Bowden, American Chemical Society, Washington,D.C., 1994. In such systems, ultraviolet (UV) light or otherelectromagnetic radiation impinges on a material containing aphotoactive component to induce a physical or chemical change in thatmaterial. A useful or latent image is thereby produced which can beprocessed into a useful image for semiconductor device fabrication.

Although the polymer product itself may be photoactive, generally aphotosensitive composition contains one or more photoactive componentsin addition to the polymer product. Upon exposure to electromagneticradiation (e.g., UV light), the photoactive component acts to change therheological state, solubility, surface characteristics, refractiveindex, color, electromagnetic characteristics or other such physical orchemical characteristics of the photosensitive composition as describedin the Thompson et al. publication supra.

For imaging very fine features at the submicron level in semiconductordevices, electromagnetic radiation in the far or extreme ultraviolet.(UV) is needed. Positive working resists generally are utilized forsemiconductor manufacture. Lithography in the UV at 365 nm (1-line)using novolak polymers and diazonaphthoquinones as dissolutioninhibitors is a currently established technology having a resolutionlimit of about 0.35-0.30 micron. Lithography in the far UV at 248 nmusing p-hydroxystyrene polymers is known and has a resolution limit of0.35-0.18 nm. There is strong impetus for future photolithography ateven shorter wavelengths, due to a decreasing lower resolution limitwith decreasing wavelength (i.e., a resolution limit of 0.18-0.12 micronfor 193 nm imaging and a resolution limit of about 0.07 micron for 157nm imaging). Photolithography using 193 nm exposure wavelength (obtainedfrom an argon fluorine (ArF) excimer laser) is a leading candidate forfuture microelectronics fabrication using 0.18 and 0.13 μm design rules.Photolithography using 157 nm exposure wavelength (obtained from afluorine excimer laser) is a leading candidate for futuremicrolithography further out on the time horizon (beyond 193 nm)provided suitable materials can be found having sufficient transparencyand other required properties at this very short wavelength. The opacityof traditional near UV and far UV organic photoresists at 193 nm orshorter wavelengths precludes their use in single-layer schemes at theseshort wavelengths.

Development of photoresist compositions having one or more protectedacidic groups may be by catalysis of acids or bases generatedphotolytically from photoactive compounds (PACs) which yield hydrophilicacid groups. A given protected acid group is one that is normally chosenon the basis of its being acid labile, such that when photoacid isproduced upon imagewise exposure, the acid will catalyze deprotectionand production of hydrophilic acid groups for development under aqueousconditions.

Examples of components having protected acidic groups that yield anacidic group as the hydrophilic group upon exposure to photogeneratedacid include, but are not limited to, A) esters capable of forming, orrearranging to, a tertiary cation, B) esters of lactone, C) acetalesters, D) β-cyclic ketone esters, E) α-cyclic ether esters, F) MEEMA(methoxy ethoxy ethyl methacrylate) and other esters which are easilyhydrolyzable because of anchimeric assistance, G) carbonates formed froma fluorinated alcohol and a tertiary aliphatic alcohol. Some specificexamples in category A) are t-butyl ester, 2-methyl-2-adamantyl ester,and isobornyl ester. Some specific examples in category B) areγ-butyrolactone-3-yl, γ-butyrolactone-2-yl, mavalonic lactone,3-methyl-γ-butyrolactone-3-yl, 3-tetrahydrofuranyl, and 3-oxocyclohexyl.Some specific examples in category C) are 2-tetrahydropyranyl,2-tetrahydrofuranyl, and 2,3-propylenecarbonate-1-yl. Additionalexamples in category C) include various esters from addition of vinylethers, such as, for example, ethoxy ethyl vinyl ether, methoxy ethoxyethyl vinyl ether, and acetoxy ethoxy ethyl vinyl ether.

It has been found that these protecting groups may generate volatileproducts during exposure because of deprotection before anypost-exposure heating step, especially as exposure wavelengths aredecreased for new imaging systems. Production of volatile products onexposure is disadvantageous since such volatiles can coat exposuredevice lenses and negatively affect their imaging properties, requiringexpensive cleaning processes. Loss of volatile material can also causeshrinkage in the imaged areas of the photoresists and negatively affectimage quality.

JP 11012326 publication discloses the following reaction:

This suggests that the lactone ring can be opened by photoacidcatalysis, but also clearly indicates that this reaction requires thepresence of moisture, and that the reaction is terminated in the absenceof moisture. In this process water as an external agent is used forreaction. Processes not requiring an external agent, in addition to aphotoacid generator, would be advantageous.

There is a need for protecting groups for polymer resist compositions,for use particularly at 193 nm or 157 nm, that provide deprotectionwithout the generation of volatiles.

SUMMARY OF THE INVENTION

Volatile components are those materials that will evaporate out of thepolymeric ingredients of the photoresist composition causing coating ofexposure lenses, and a loss of polymer mass that may lead to poor imagequality. The invention is related to incorporating a protecting groupand a polar group (that is to be protected) in a cyclic structure sothat volatile components are not released during deprotection of thepolar group by photogenerated catalyst leading to solubility indeveloper. This approach can be used for both the polymeric binder ofthe photoresist composition and/or the dissolution inhibitor of thephotoresist composition.

In a first aspect, the invention provides a photoresist compositioncomprising:

-   -   (a) a protected material comprising:        -   A. one or more cyclic ether groups having structure I or II:            wherein R_(f) and R_(f)′ independently represent fluoroalkyl            groups of from one to about ten carbon atoms or taken            together are (CF₂)_(a) wherein a is an integer ranging from            2 to about 10, R independently represents a hydrogen atom or            a straight chain or branched chain alkyl group of 1 to about            10 carbon atoms, and p is an integer of from 0 to about 8;            wherein the protected material is substantially free of an            acid group with a pKa of <11; and    -   (Y) one or more cyclic esters having structure III:        wherein R₁ and R₂ independently represent an unsubstituted        straight chain or branched chain alkyl group having 1 to 10        carbon atoms; aromatic, aralkyl, or alkaryl group having 6 to 14        carbon atoms; or substituted groups thereof containing at least        one O, S, N, P or halogen; and n is an integer ranging from 1 to        about 4; and    -   (b) a photoactive component.

In a second aspect, the invention relates to a process for preparing aphotoresist image on a substrate comprising, in order:

-   -   (W) providing a photoresist layer on a substrate, wherein the        photoresist layer is prepared from a photoresist composition        comprising:    -   (a) a protected material comprising a group which is:        -   A. one or more cyclic ether groups having structure I or II:            wherein R_(f) and R_(f)′ independently represent fluoroalkyl            groups of from one to about ten carbon atoms or taken            together are (CF₂)_(a) wherein a is an integer ranging from            2 to about 10, R independently represents a hydrogen atom or            a straight chain or branched chain alkyl group of 1 to about            10 carbon atoms, and p is an integer of from 0 to about 8;            wherein the protected material is substantially free of an            acid group with a pKa of <11; and    -   B. one or more cyclic esters having structure III:        wherein R₁ and R₂ independently represent an unsubstituted        straight chain or branched chain alkyl group having 1 to 10        carbon atoms; aromatic, aralkyl, or alkaryl group having 6 to 14        carbon atoms; or substituted groups thereof containing at least        one O, S, N, P or halogen; n is an integer ranging from 1 to        about 4; and    -   (b) a photoactive component;        -   (X) imagewise exposing the photoresist layer to form imaged            and non-imaged areas; and        -   (Y) developing the exposed photoresist layer having imaged            and non-imaged areas to form the relief image on the            substrate.

An example of a cyclic ether group represented by (A) is an oxetanegroup having the following structure:

An example of a cyclic ester group represented by (B) is provided by asubstituted lactone having the following structure:

A polymer containing this group can be obtained by incorporating thedimethyl tulipalin monomer (γ,γ-dimethyl-α-methylene-γ-butyrolactone).The deprotection of these two classes of protecting groups is catalyzedby photogenerated acid without the requirement that moisture be presentand without the generation of volatiles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Protecting Groups:

The protected material comprises a protecting group selected from thegroup consisting of one or more cyclic ether groups or cyclic estergroups having the structures A or B, as shown above.

Materials containing a cyclic ether group represented by structure I maybe prepared, for example, by hypochlorite oxidation of compoundscontaining the —CH═CR_(f)R_(f)′ fragment as described in WO2000/066575A2. Materials containing the cyclic ether protecting grouprepresented by structure 11 wherein p is 0 may be prepared, for example,by the method disclosed in U.S. Pat. No. 3,164,610 (1964) or in Izv.Akad. Nauk. Ser. Khim. 1967, pp. 918-921 using the reaction ofcorresponding vinyl ether with hexafluoroacetone. Materials containingthe cyclic ether-group wherein p is 0 to about 8 may be prepared bycyclization of α-haloethers of structure—O—CHCl-CHR—(CRR)_(p)—C(R_(f)R_(f)′)OH in the presence of base.

Cyclic ether groups of formula I or II may be converted thermally or byaction of catalytic amount of acid into a fluoroalcohol containingmaterial of formulas I′ and II′, respectively, as a result ofring-opening processes presented below:

The cyclic esters which can be converted into a carboxylic acid may besubstituted lactones which open in the presence of strong acid. Anexample is the polymerizable monomer, dimethyl tulipalin(γ,γ-dimethyl-α-methylene-γ-butyrolactone. Such functional groups canalso be attached to non-polymeric structures.

The point of attachment of the protected material to the protectinggroup in structure I or II will be to a carbon atom which is asubstituent of the ether ring. At least one point of attachment of theprotected material to the protecting group in structure III will bethrough a saturated ring carbon of the structure or R₁ or R₂.

Protected Material:

The protected material may be a binder or a dissolution inhibitor.

The binder may be a polymeric binder. Examples include all polymersuseful as photoresists such as those of the type disclosed in WO00/17712 published Mar. 20, 2000, WO 00/25178 published May 4, 2000, andPCT/US00/11539 filed Apr. 28, 2000, with the proviso that thephotoresist composition in its unexposed state does not have acid groupswith a pKa of <11, typically <12, and more typically <14 when theprotecting group is a cyclic ether represented by Structures 1 and 11.

The polymer binder may be a fluorine-containing polymer. Thefluorine-containing polymer may further comprise a repeat unit derivedfrom at least one ethylenically unsaturated compound containing afunctional group having the structure:—C(R_(f))(R_(f)′)OR₃wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom 1 to about 10 carbon atoms or taken together are (CF₂)_(n) whereinn is 2 to about 10, and R₃ is a hydrogen atom or an acid labileprotecting group, when the protected material is a cyclic ether group R₃is an acid labile protecting group.

The fluoroalkyl groups designated as R_(f) and R_(f)′, can be partiallyfluorinated alkyl groups or fully fluorinated alkyl groups (i.e.,perfluoroalkyl groups).

Broadly, R_(f) and R_(f)′ are each independently represented byfluoroalkyl groups of from 1 to about 10 carbon atoms or taken togetherare (CF₂)_(n) wherein n is an integer ranging from 2 to about 10. Theterms “taken together” mean that R_(f) and R_(f) are not separate,discrete fluorinated alkyl groups, but that together they form a ringstructure of 3 to about 11 carbon atoms such as is illustrated below incase of 5-membered rings:

When R_(f) and R_(f)′ are partially fluorinated alkyl groups there mustbe a sufficient degree of fluorination present to impart acidity to thehydroxyl (—OH) of the ring opened form, such that the hydroxylproton issubstantially removed in basic media, such as in aqueous sodiumhydroxide solution or tetraalkylammonium hydroxide solution. Typically,there will be sufficient fluorine substitution present in thefluorinated alkyl groups of the fluoroalcohol functional group in thering opened form such that the hydroxyl group will have a pKa value asfollows: 5<pKa<11.

Preferably, R_(f) and R_(f)′ are independently perfluoroalkyl group of 1to about 5 carbon atoms, and, most preferably, R_(f) and R_(f)′ are bothtrifluoromethyl (CF₃). A protected material containing the protectinggroup of structure II when p is 0 or 1 and R is a hydrogen atom arepreferred.

When the protected material is a polymeric binder, it may also beprepared from ethylenically unsaturated monomers by free radicalpolymerization or metal-catalyzed vinyl addition polymerizationprocesses known in the art to afford a polymer having a repeat unit thatis derived from the ethylenically unsaturated monomer. Specifically, anethylenically unsaturated compound having structure:

that undergoes free radical polymerization will afford a polymer havinga repeat unit:

where P, Q, S, and T independently can be the same or different andillustratively could be fluorine, hydrogen, chlorine, andtrifluoromethyl.

If only one ethylenically unsaturated compound undergoes polymerization,the resulting polymer is a homopolymer. If two or more distinctethylenically unsaturated compounds undergo polymerization, theresulting polymer is a copolymer.

Some representative examples of ethylenically unsaturated compounds andtheir corresponding repeat units are described below:

For metal catalyzed vinyl addition polymerization a useful catalyst is anickel containing complex. Neutral Ni catalysts are described in WO9830609. Other references regarding the salicylaldimine-based neutralnickel catalysts include WO Patent Application 9842664. Wang, C.;Friedrich, S.; Younkin, T. R.; Li, R. T.; Grubbs, R. H.; Bansleben, D.A.; Day, M. W. Organometallics 1998, 17 (15), 314 and Younkin, T.;Connor, E. G.; Henderson, J. I.; Friedrich, S. K.; Grubbs, R. H.;Bansleben, D. A. Science 2000, 287, 460462. Additional catalysts aredisclosed in Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. Rev.2000, 100, 1169-1203 and Boffa, L. S.; Novak, B. M. Chem. Rev. 2000,100, 1479-1493. Moody, L. S.; MacKenzie, P. B.; Killian, C. M.; Lavoie,G. G.; Ponasik, J. A.; Barrett, A. G. M.; Smith, T. W.; Pearson, J. C.WO 0050470 discloses improvements or variations of largely existingligands and some new ligands on late metal catalysts, e.g., ligandsderived from pyrrole amines instead of anilines and also ligands basedon anilines with 2,6-ortho substituents where these ortho substituentsare both aryl groups or any aromatic group. Specific examples would bealpha-diimine-based nickel catalysts and salicylaldimine-based nickelcatalysts derived from the pyrrole amines and ortho-aromatic-substitutedanilines. Some of these derivatives show improvedlifetimes/activities/productivities/hydrogen response/potentialfunctional group tolerance, etc. Another useful catalyst is a functionalgroup tolerant, late metal catalyst usually based on Ni(II) or Pd(II).Useful catalysts are disclosed in WO 98/56837 and U.S. Pat. No.5,677,405.

Any suitable polymerization conditions may be employed in the process ofmaking the polymer. Typically, when metal catalyzed vinyl additionpolymerization is used the temperatures are held below about 80° C.,typically between 20° C. and 80° C. Suitable known solvents may be usedsuch as trichlorobenzene or p-xylene.

It is desirable that binder polymers used in photoresist compositions behighly transparent at the wavelength of light used for creating thephotoimage. Preferably, the binder has an absorption coefficient of lessthan 4.0 μm⁻¹, more preferably of less than 3.5 μm⁻¹, and, still morepreferably, of less than 2.5 μm⁻¹ at the wavelength. As shown in anexample, binder polymers having the fluorinated cyclic ether groupingcan have a high degree of transparency at 157 nm making thesecompositions especially useful at this wavelngth.

Some illustrative, but nonlimiting, examples of comonomers containing afluorinated cyclic ether group within the scope of this invention arepresented below:

The fluorine-containing binder polymer of this invention may, optionallycomprise additional protected fluoroalcohol functional groups. Someillustrative, but not limiting examples of representative comonomerscontaining protected fluoroalcohol groups are described below:

 CH₂═CHO(CH₂)₂OCH₂C(CF₃)₂OCH₂OCH₃

The fluorine-containing polymer may be photactive, i.e. the photoactivecomponent may be chemically bonded to the fluorine-containing polymer.This may be accomplished by chemically bonding the photoactive componentto a monomer which then undergoes copolymerization to the monomers, thuseliminating the need for a separate photoactive component.

A fluorine-containing polymer of this invention may comprise a repeatunit derived from at least one ethylenically unsaturated compoundcharacterized in that at least one ethylenically unsaturated compound ispolycyclic and at least one ethylenically unsaturated compound containsat least one fluorine atom covalently attached to an ethylenicallyunsaturated carbon atom.

One or more additional monomers may be used in the preparation of thefluorine-containing polymers. In general, it is contemplated that anacrylate monomer may be suitable as the additional monomer in preparingthe polymers. Typical additional monomers include acrylates, olefinscontaining electron-withdrawing groups (other than fluorine) directlyattached to the double bond. These terpolymers may be made byfree-radical polymerization, for example, acrylonitrile, vinyl chloride,vinylidene chloride. Vinyl acetate is also useful as an additionalmonomer.

Alternately, the fluorine-containing polymer may contain a spacer group.

The spacer group is a hydrocarbon compound containing vinylicunsaturation and optionally, containing at least one heteroatom, such asan oxygen atom or a nitrogen atom. The hydrocarbon compound contemplatedas the spacer group contains, typically, 2 to 10, more typically 2 to 6carbon atoms. The hydrocarbon may be straight chain or branched chain.Specific examples of suitable spacer groups are selected from the groupconsisting of ethylene, alpha-olefins, 1,1′-disubstituted olefins, vinylalcohols, vinyl ethers, and 1,3-dienes. Typically, when the spacer groupis and alpha olefin, it is selected from the group consisting ofethylene, propylene, 1-butene, 1-pentene, 1-hexene and 1-octene.Typically, when the spacer group is a vinyl ether it is selected fromthe group consisting of methyl vinyl ether and ethyl vinyl ether.Typically vinyl alcohols would be obtained by post-polymerizationhydrolysis of a functional group already incorporated into the polymerbackbone, e.g. the acetate group of vinyl acetate. Typically when thespacer group is a 1,3-diene it is butadiene. Typically when the spacergroup is a 1,1′-disubstituted olefin it is isobutylene or isopentene.

The ratio of spacer group containing monomer and other monomers can beimportant. Typical ranges for each are about 30% to about 70%.Alternately, spacer groups selected from the group consisting ofethylene, alpha-olefins, 1,1′-disubstituted olefins, vinyl alcohols,vinyl ethers, and 1,3-dienes may be present in the polymer. Otherpolymer types such as methacrylates and acrylates may also be used.

The quantity of polymeric binder in the photoresist composition may bein the amount of about 50 to about 99.5 weight % based on the totalweight of the photoresist composition (solids).

Photoactive Component (PAC)

The photoresist composition contains a combination of binder andphotoactive component.

If the polymer of the binder itself is photoactive, a separatephotoactive component is not required. It is contemplated that thephotoactive component may be chemically bonded to the polymer of thebinder. A system in which the polymeric binder itself is photochemicallyactive is described in EP 473547. Therein a photoresist comprises anolefinically unsaturated sulfonium or iodonium salt (the photochemicallyactive component) copolymerized with an olefinically unsaturatedcomonomer containing an acid sensitive group yielding a radiationsensitive copolymer that would be an effective photoactive polymericbinder.

When the compositions of this invention contain a separate photoactivecomponent (PAC) the binder itself is usually not photactive.

The photoactive component (PAC) usually is a compound that produceseither acid or base upon exposure to actinic radiation. If an acid isproduced upon exposure to actinic radiation, the PAC is termed aphotoacid generator (PAG). If a base is produced upon exposure toactinic radiation, the PAC is termed a photobase generator (PBG).

Suitable photoacid generators for this invention include, but are notlimited to, 1) sulfonium salts (structure A), 2) iodonium salts(structure B), and 3) hydroxamic acid esters, such as structure C.

In structures IV-V, R₁-R₃ are independently substituted or unsubstitutedaryl or substituted or unsubstituted C₁-C₂₀ alkylaryl (aralkyl).Representative aryl groups include, but are not limited to, phenyl andnaphthyl. Suitable substituents include, but are not limited to,hydroxyl (—OH) and C₁-C₂₀ alkyloxy (e.g., C₁₀H₂₁O). The anion X— instructures IV-V can be, but is not limited to, SbF₆—(hexafluoroantimonate), CF₃SO₃-(trifluoromethylsulfonate=triflate), andC₄F₉SO₃-(perfluorobutylsulfonate).

Dissolution Inhibitor

When the protected material of this invention is a dissolutioninhibitor, it includes compounds which have been found to have asufficiently low absorption coefficient for use in microlithography atthe imaging wavelengths. Specifically, the compounds of this inventionmay have an absorption coefficient of less than about 4.0 μm⁻¹ at awavelength of 157 nm, typically, less than about 3.5 μm⁻¹ at awavelength of 157 nm, and still more typically less than about 3.0 μm⁻¹at a wavelength of 157 nm and still more typically less than about 2.5μm⁻¹ at a wavelength of 157 nm. Dissolution inhibitors may satisfymultiple functional needs including dissolution inhibition, plasma etchresistance, plasticising and adhesion behavior of resist compositions.

The protected material may be a dissolution inhibitor. The dissolutioninhibitor usually comprises a paraffinic or cycloparaffinic oroligomeric compound. The dissolution inhibitor may have a structurecomprising the same monomer components as the binder but usually it hasa lower molecular weight than the polymer of the binder. For example,the dissolution inhibitor may contain a at least one functional grouphaving the structure:—C(R_(f))(R_(f)′)OR₃as described above. The dissolution inhibitor may also comprise a cyclicester that can be opened by photogenerated acid in the absence ofmoisture.

However, when the protected material is a dissolution inhibitor, thepolymeric binder may be any polymer which has the transparencyproperties suitable for use in microlithography. It is contemplated thatbinders suitable for the present invention may include those polymerswhich are typically incorporated into chemically amplified 248 (deep UV)and 193 nm photoresists for imaging at longer wavelengths. A typical 248nm resist binder is based on polymers of para-hydroxystyrene. Otherexamples of suitable 248 nm resist binders can be found in the referenceIntroduction to Microlithography, Second Edition by L. F. Thompson, C.G. Willson, and M. J. Bowden, American Chemical Society, Washington,D.C., 1994, chapter 3. Binders useful for 193 nm photoresists includecycloolefin-maleic anhydride alternating copolymers [such as thosedisclosed in F. M. Houlihan et al., Macromolecules, 30, pages 6517-6534(1997); T. Wallow et al., Proc. SPIE, 2724, 355; and F. M. Houlihan etal., Journal of Photopolymer Science and Technology, 10, 511(1997)],polymers of functionalized norbornene-type monomers prepared bymetal-catalyzed vinyl addition polymerization or ring-opening metathesispolymerization [such as those disclosed in U. Okoroanyanwu et al. J.Mol. Cat A: Chemical 133, 93 (1998), and PCT WO 97/33198], and acrylatecopolymers [those described in U.S. Pat. No. 5,372,912]. Photoresistbinders that are suitable for use with this invention also include thosewhich are transparent at wavelengths below 248 and 193 nm such as thosepolymers containing fluoroalcohol functional groups [such as thosedisclosed in K. J. Pryzbilla et al. Proc. SPIE 1672, 9 (1992), and H.Ito et al. Polymn. Mater. Sci. Eng. 77, 449 (1997)].

Typical examples of polymers which are also useful as a dissolutioninhibitor are those which have been developed for use in chemicallyamplified photoresists which are imaged at an irradiation wavelength of157 nm. Specific examples of such polymers are fluoropolymers andfluoropolymers containing fluoroalcohol functional groups. Suitableexamples have been disclosed in WO 00/17712, WO 00/25178 andPCT/US00/11539 filed Apr. 28, 2000, with the proviso that thephotoresist composition in its unexposed state does not have acid groupswith a pKa of <11, typically <12, and more typically <14 when theprotecting group is a cyclic ether represented by Structures 1 and 11.

Dissolution inhibitors having the protecting groups of this inventionmay comprise a paraffinic or cycloparaffinic compound containing atleast one protecting group, typically at least two, more typically 2 toabout 10 and most typically 2 to 3 cyclic ether protecting groups havingstructure I, II or III as described above.

Typically, when the compound contains at least 2 of the protectinggroups there is improved solubility of the dissolution inhibitor in thedeveloped form and less solubility in the undeveloped form.

Typically, R_(f) and R_(f)′ are independently a perfluoroalkyl group of1 to about 5 carbon atoms, more typically a perfluoroalkyl group of 1 toabout 3 carbon atoms, and most typically R_(f) and R_(f)′ are bothtrifluoromethyl (CF₃).

The fluoroalkyl groups, designated as R_(f) and R_(f)′, can be partiallyfluorinated alkyl groups or fully fluorinated alkyl groups (i.e.,perfluoroalkyl groups), as described above.

In preferred cases according to the invention, there will be sufficientfluorine substitution present in the fluorinated alkyl groups of thefluoroalcohol functional group such that the hydroxyl group will have apKa value as follows: 5<pKa<11.

In one aspect, the dissolution inhibitor is an oligomer comprising arepeat unit derived from at least one ethylenically unsaturated compoundcontaining a protected fluoroalcohol functional group having one or moreA cyclic ether group or B cyclic ester group, the structures of whichare described above.

An oligomer is a low molecular weight polymer (e.g. dimer, trimer,tetramer), in the present case, with a number average molecular weightof less than or equal to 3000. As is well known to those skilled in theart, certain ethylenically unsaturated compounds (monomers) undergo freeradical polymerization or metal-catalyzed addition polymerization toform polymers having repeat unit(s) derived from the ethylenicallyunsaturated compounds. By suitable adjustments in polymerizationconditions and especially by employing a chain transfer agent or chainterminating agent in the synthesis, the molecular weight of the productmay be controlled to the desired range. Chain transfer agents which areuseful for controlling molecular weight in free radical polymerizationsare well known in the art and include primary and seconday alcohols,such as methanol, ethanol and 2-propanol, chlorocarbons, such as carbontetrachloride, and thiols, such as dodecyl mercaptan. Transitionmetal-catalyzed addition polymerization of monomers containing cyclicfluorinated ether groups may be employed. Molecular weight can bereduced so as to form oligomers by the addition of suitablechain-transfer agents; for example, hydrogen, silanes, or olefins suchas ethylene, propylene, or 1-hexene. The use of olefins to control andreduce molecular weight in polymerizations of norbornene-type monomerscatalyzed by nickel and palladium catalysts is known in the art; forexample, see U.S. Pat. No. 5,741,869; U.S. Pat. No. 5,571,881; U.S. Pat.No. 5,569,730 and U.S. Pat. No. 5,468,819.

Some illustrative, but nonlimiting, examples of representative monomerscontaining a fluorinated ether functional group and within the scope ofthe invention are presented below:

In another aspect of this invention, the dissolution inhibitor is acompound comprising the following structures:

wherein A is a paraffinic or cycloparaffinic group containing 2 to 30carbon atoms, R_(f) and R_(f)′ are as described hereinabove b is aninteger ranging from at least 1, typically at least 2, more typically 2to about 10 and most typically 2 to 3.

The paraffinic or cycloparaffinic group is understood to be onecomprising carbon and hydrogen atoms and to be substantially free ofethylenic, acetylenic or aromatic unsaturation. The paraffinic orcycloparaffinic group may contain heteroatoms selected from the groupconsisting of fluorine, chlorine and oxgen. Such heteroatoms may formsubstituent groups which do not substantially contribute to absorptionat short wavelengths of light. Specific examples of such oxygencontaining substituent groups are hydroxyl and ether. For example, acycloparaffinic starting material is 4,4′-isopropylidenedicyclohexanol.Some illustrative, but nonlimiting, examples of dissolution inhibitorswithin the scope of this embodiment are presented below:

In cases wherein the dissolution inhibitor of this invention containsmore than one fluorinated cyclic ether group, the R_(f) and R_(f)′groups may be the same or different.

The fluorinated ether group may be used alone or it can be used incombination with one or more other protected acid groups, such asprotected fluoroalcohol or carboxylic acid groups.

The dissolution inhibitor may be prepared by processes know in the art,for example, the materials shown above containing thebis(trifluoromethyl)oxetane groups may be made by reaction ofcorresponding bisvinyl ethers with hexafluoroacetone as disclosed inU.S. Pat. No. 3,164,610 (1964) or in Izv. Akad. Nauk. Ser. Khim. 1967,pp. 918-921.

Some dissolution inhibiting compounds also serve as plasticizers inresist compositions.

A dissolution inhibiting amount of the dissolution inhibitor is combinedwith a binder and any other photoresist additives. The dissolutioninhibitor may be present in the amount of about 0.5 to about 50 weight%, more typically about 1 to about 35 weight %, and most typically about5 to about 20 weight %, based on the total weight of the photoresistcomposition (solids).

Other Components

The compositions of this invention can contain optional additionalcomponents. Examples of such additional components include, but are notlimited to, resolution enhancers, adhesion promoters, residue reducers,coating aids, plasticizers, and T_(g) (glass transition temperature)modifiers.

Process Steps

Imagewise Exposure

The photoresist compositions of this invention are sensitive in theultraviolet region of the electromagnetic spectrum and especially tothose wavelengths ≦365 nm. Imagewise exposure of the resist compositionsof this invention can be done at many different UV wavelengthsincluding, but not limited to, 365 nm, 248 nm, 193 nm, 157 nm, and lowerwavelengths. Imagewise exposure is preferably done with ultravioletlight of 248 nm, 193 nm, 157 nm, or lower wavelengths, preferably it isdone with ultraviolet light of 193 nm, 157 nm, or lower wavelengths, andmost preferably, it is done with ultraviolet light of 157 nm or lowerwavelengths. Imagewise exposure can either be done digitally with alaser or equivalent device or non-digitally with use of a photomask.Digital imaging with a laser is preferred. Suitable laser devices fordigital imaging of the compositions of this invention include, but arenot limited to, an argon-fluorine excimer laser with UV output at 193nm, a krypton-fluorine excimer laser with UV output at 248 nm, and afluorine (F2) laser with output at 157 nm. Since, as discussed supra,use of UV light of lower wavelength for imagewise exposure correspondsto higher resolution (lower resolution limit), the use of a lowerwavelength (e.g., 193 nm or 157 m or lower) is generally preferred overuse of a higher wavelength (e.g., 248 nm or higher).

Development

The polymers in the resist compositions of this invention must containsufficient functionality for development following imagewise exposure toUV light. Typically, the functionality is acid or protected acid suchthat aqueous development is possible using a basic developer such assodium hydroxide solution, potassium hydroxide solution, or ammoniumhydroxide solution. The protecting groups of the present invention areadvantageous since they do not require moisture to deprotect thedevelopable group, in addition to not yielding a volatile deprotectionproduct due to the cyclic nature of the protecting group.

When an aqueous processable photoresist is coated or otherwise appliedto a substrate and imagewise exposed to UV light, development of thephotoresist composition may require that the binder material shouldcontain sufficient protected acid groups that are at least partiallydeprotected upon exposure to render the photoresist (or otherphotoimageable coating composition) processable in aqueous alkalinedeveloper. In case of a positive-working photoresist layer, thephotoresist-layer will be removed during development in portions whichare exposed to UV radiation but will be substantially unaffected inunexposed portions during development by aqueous alkaline liquids suchas wholly aqueous solutions containing 0.262 N tetramethylammoniumhydroxide (with development at 25° C. usually for less than or equal to120 seconds). In case of a negative-working photoresist layer, thephotoresist layer will be removed during development in portions whichare unexposed to UV radiation but will be substantially unaffected inexposed portions during development using either a critical fluid or anorganic solvent.

A critical fluid, as used herein, is one or more substances heated to atemperature near or above its critical temperature and compressed to apressure near or above its critical pressure. Critical fluids in thisinvention are at least at a temperature that is higher than 15° C. belowthe critical temperature of the fluid and are at least at a pressurehigher than 5 atmospheres below the critical pressure of the fluid.Carbon dioxide may be used for the critical fluid in the presentinvention.

Various organic solvents can also be used as developer in thisinvention. These include, but are not limited to, halogenated solventsand non-halogenated solvents. Halogenated solvents are preferred andfluorinated solvents are more preferred.

Substrate

The substrate employed in this invention can illustratively be silicon,silicon oxide, silicon nitride, or various other materials used insemiconductive manufacture.

EXAMPLES Example 1

A compound having the following structure was prepared using thefollowing procedure:

25 g of vinyl ether prepared from exo-5-norbornen-2-ol were dissolved in100 mL of ether, 0.5 g of potassium carbonate was added to a solutionand 32 g of hexafluoroacetone (5% excess) fed into reaction vessel as agas at 10-15° C. The reaction mixture was brought to 25° C. and wasagitated at this temperature for 1 h. The solvent was removed undervacuum at 30° C. and the crude product was distilled under vacuum togive 34.8 g (63%) of product >95% purity, b.p. 50-52° C./0.38 mm Hg.

¹H NMR (CDCl₃): 1.3-1.8 (4H), 2.7-3.1 (4H), 3.8 (2H), 5.6 (1H), 5.8(1H), 6.1 (1H) ppm, ¹⁹F NMR (CDCl₃): −79.13 (3F, m), −79.28 (3F, m)PPM.

Example 2

Oxetane A monomer having the following structure was prepared using thefollowing procedure:

22.8 g (0.2 mol) of CH₂═CHO(CH₂)₂OCH═CH₂ were dissolved in 100 mL of dryether, and 33 g (0.2 mol) of hexafluoroacetone were introduced intoreactor as a gas at −20° C. The reaction mixture was maintained at −15°C. for 30 min, warmed up to 25° C., solvent was removed under vacuum andresidue (55 g) was distilled under reduced pressure in the presence of0.1 g of K₂CO₃ to give 26 g (46.6%) of fraction b.p. 43-48° C./0.25 mmHg (major fraction 45-46° C.), which was found to be the title compoundof >98% purity. The residue 25 g based on NMR data was mostly theproduct of condensation of one mole of divinyl ether with two moles ofhexafluoroacetone.

¹H NMR (acetone-d₆): 2.60 (1H), 2.8 (1H, dd), 3.15 (1H, dd), 3.64.2(5H), 5.65 (1H,t), 6.35 (1H, dd) PPM; ¹⁹F NMR (acetone-d₆): -79.72 (3F,m), −79.83 (3F, m) PPM.

Example 3

A Bis(trifluorooxetane)-containing polymer was synthesized using thefollowing procedure:

A 200 mL stainless steel autoclave was charged with 15.4 g (0.08 mol) ofadamantanemethylvinyl ether (AdVether), 22.4 g (0.08 mol) of the oxetanemonomer of Example 2 (OXVE), 50 mL of tert-butanol, 25 mL ofisopropanol, 0.5 g of potassium carbonate and 0.4 g of Vazo® 52. Thevessel was closed, cooled, evacuated and purged with nitrogen severaltimes. It was then charged with 24.0 g (0.24 mol) of tetrafluoroethylene(TFE). The autoclave was agitated with the vessel contents at 50° C. forabout 18 hr resulting in a pressure change from 294 psi to 134 psi. Thevessel was cooled to room temperature and vented to one atmosphere. Thevessel contents were removed using acetone to rinse giving a clearslightly yellow solution. This solution was added slowly to excess icewater resulting in precipitation of a white polymer which was driedovernight in a vacuum oven. The yield was 49.8 g (81%). GPC analysis:Mn=35,500; Mw=73300; Mw/Mn=2.06. DSC analysis: A Tg of 35° C. wasobserved on second heat. ¹H NMR (δ, THF-d8) 1.48-2.05 (m, 15H fromadamantane rings), 2.37-2.80 (m, CH₂ from polymer backbone), 2.91 (m, 1oxetane ring H), 3.15 (m, 1 oxetane ring H), 3.20-3.40 (m, CH₂O attachedto adamantane ring), 3.87: (m, OCH₂CH₂O attached tooxetane ring), 4.22and 4.40 (m, CH on polymer backbone), 5.68 (m, acetal hydrogen). Byintegration, the ratio of OXVE to AdVether in the polymer is 57:43. ¹⁹FNMR (δ, THF-d8)-78.9 (CF₃), −107 to −125 (CF₂). From the fluorine NMR,the ratio of OXVE to TFE in the polymer is 33 to 67. Combining theseratios suggests an overall composition of 53% TFE, 20% AdVether and 26%OXVE. Anal. Found: C, 46.34; H, 4.43; F, 37.96.

Example 4

A Bis(trifluoromethyl)oxetane-containing polymer was prepared using thefollowing procedure:

A 200 mL stainless steel autoclave was charged with 16.0 g (0.17 mol) ofnorbornene, 21.1 g (0.07 mol) of the oxetane-containing monomer ofExample 1 (NB-OX), 75 mL of 1,1,2-trichlorotrifluoroethane, 0.5 g ofpotassium carbonate and 1.0 g of Perkadox® 16. The vessel was closed,cooled, evacuated and purged with nitrogen several times. It was thencharged with 30 g (0.30 mol) of tetrafluoroethylene (TFE). The autoclavewas agitated with the vessel contents at 50° C. for about 18 hrresulting in a pressure change from 228 psi to 201 psi. The vessel wascooled to room temperature and vented to one atmosphere. The vesselcontents were removed using 1,1,2-trichlorotrifluoroethane to rinsegiving a clear solution. This solution was added slowly to excessmethanol resulting in precipitation of a white polymer which was driedover night in a vacuum oven. Yield was 17.1 g (25%). GPC analysis:Mn=5200; Mw=8200; Mw/Mn=1.57. DSC analysis: A Tg of 111° C. was observedon second heat. The fluorine NMR spectrum showed peaks at −76.8 to −78.6ppm (CF₃) and −95 to −125 ppm (CF₂) confirming incorporation of NB-OXand TFE, respectively, in a ratio of 1:2.8. A thin film of the polymerobtained by spin coating from a 2-heptahone solution showed anabsorbance of 1.33 μm⁻¹ at 157 nm, indicating a high degree of opticaltransparency at this wavelength.

Analysis found: C, 52.03; H, 4.79; F, 37.22.

Example 5

The oxetane containing polymer was isomerized using the followingprocedure:

6 g of TFE/AdVether/OXVE terpolymer prepared in Example 3, weredissolved in 80 mL of ether and 0.1 g of 96% H₂SO₄ was added dropwiseover a period of 5 min, to keep temperature of reaction mixture <25° C.and reaction mixture was agitated at ambient temperature for 1 h.Slightly yellow solution was filtered through glass wool. Based on NMRthe solution at this point did not contain any material containingoxetane ring. ¹H NMR spectrum of the material exhibit two dublets at 4.9and 7.1 PPM, typical of vinyl protons of CH═CH fragment (1H NMR ofstarting material contained only one signal in this region −6 PPM); ¹⁹Fspectrum contained only one signal at −79.0 PPM (two signals −79.01 and−79.2 PPM in starting material). Solvent was removed under vacuum toleave 5.2 g of slightly yellow polymer, which was not soluble in ether,acetone and ethyl acetate. 4.5 g of this material was dissolved in 30 mLof dimethylacetamide at 60-70° C. (4 h) and the solution was left atambient temperature for 2 days. Precipitate formed was separated fromliquid, washed with H₂O, filtered, washed with methanol and air-dry for1 hr. at 25° C. 4 g of white polymer were isolated. In IR spectrum ofthis material (KBr) were found two new bands at 1633 (C═C) and 3433(OH), which were not present in IR spectrum of starting material.

Example 6 Preparation of Gamma,Gamma-Dimethyl-Alpha-Methylene-Gamma-Butyrolactone

(g,g-dimethylMBL, or DM-MBL)

Example 6a Preparation of Triisopropylbenzenesulfonyl Hydrazide

A 500 mL, three neck flask with a mechanical stirrer, thermometer,addition funnel, and a condenser with nitrogen tee was charged with2,4,6-triisopropylbenzenesulfonyl chloride (100 g, 0.33 mol) and THF(120 mL) and cooled to 10° C. Hydrazine monohydrate (36 g, 0.73 mol) wasadded dropwise via addition funnel over 20 minutes (exothermic) whilemaintaining the temperature at 10-15° C. The reaction became a yellowslurry, then a cloudy solution, then a yellow slurry. At the end of theaddition, a precipitate formed. Another 80 mL THF were added and thesolids dissolved to give a yellow solution. The mixture was stirred for30 min. Two layers were visible. The organic layer (top layer) waswashed with 100 mL sat'd NaCl, dried over MgSO4, filtered, andconcentrated on the rotary evaporator to obtain a light yellow solid.The solid was triturated with petroleum ether, filtered, and washed with300 mL petroleum ether. The solid was dried overnight under a nitrogenstream to obtain the desired product (88 g theory 98.7 g) as a whitesolid. Another 4 g of the desired product were obtained by concentrationof the filtrate and triturating with petroleum ether. ¹H NMR (500 MHz,CDCl3) δ 1.2 (s, 18H), 3.0 (m, 1H), 3.5 (brs, 2H), 4.0 (m, 2H), 5.5(brs, 1H), 7.3 (d, 2H); 13C NMR (125 MHz, CDCl3) δ 23.30, 24.68, 29.50,34.02, 123.82, 128.50, 151.64, 153.63.

Example 6b Preparation of Acetone 2,4,6-TriisopropylbenzenesulfonylHydrazide

A 500 mL, 3 neck flask equipped with a mechanical stirrer, thermometer,addition funnel, and a condenser with nitrogen tee was charged with 300mL acetone and add 2,4,6-triisopropylbenzenesulfonyl hydrazine (87.9 g,0.29 mol) with stirring. Caution: the temperature rises from 20° C. to30° C. upon addition of the solid. Concentrated HCl (1 mL) was added andthe cloudy solution was stirred for 1 hour. The desired product (solid)precipitates over the course of the reaction. The mixture was filteredand the solids washed with water (2×200 mL), and dried with a nitrogensweep to obtain 30.7 g of the desired product. The filtrate was slowlypoured in to 300 mL water with cooling to give a white slurry. Theslurry was stirred for 15 minutes, filtered, washed with 250 mL water,and dried under a nitrogen stream to obtain 64.2 g of the desiredproduct as a white solid. Combined yield: 64.2 g+30.7 g=94.9 g (96%). ¹HNMR (500 MHz, CDCl3) δ 1.75 (s, 18H), 1.9 (s, 3H), 1.95 (s, 3H), 2.5 (m,1H), 4.1 (m, 2H), 7.2 (s, 2H); ¹³C NMR (125 MHz, CDCl3) δ 16.37, 23.46,24.70, 24.84, 25.25, 29.83, 34.05, 123.68, 131.42, 151.29, 153.00,154.06.

Example 6c Preparation of g,g-dimethyl-MBL (DM-MBL)

A 2000 mL, 3 neck flask equipped with a mechanical stirrer, thermometer,addition funnel, and a condenser with nitrogen tee was charged with 250mL dimethoxyethane, acetone 2,4,6-triisopropyltosylhydrazone (45 g,0.133 mol), and cooled to −78° C. in a dry ice/acetone bath. To this wasadded 2.4 equivalents of n-butyl lithium in hexanes (20.4 g, 0.32 mol,128 mL) via addition funnel under nitrogen. The reaction changed fromclear to orange to yellow/orange. The temperature was allowed to rise to−50° C. over 10 minutes. To this was added acetone (13.7 g, 0.236 mol,1.77 equivalents) dropwise via syringe while maintaining −50° C.temperature (exothermic reaction with acetone). The reaction turns fromorange/yellow to almost clear upon acetone addition. The reaction wascooled to −78° C., then another 1.8 equivalents n-butyl lithium (15.3 g,0.24 mol, 96 mL) were added dropwise. The reaction turned from almostclear to yellow/orange to red/orange and was allowed to stir at −78° C.for 8 minutes then allowed to warm to −5° C. over 45 minutes. It wasthen held for one hou (at −5° C., and then cooled back to −78° C. (dryice/acetone) and quenched by bubbling in CO₂ gas 10 min (slow, evenbubbling, caution, exothermic reaction). The reaction was allowed towarm to room temperature and quenched with 400 mL cold water (CAUTION,add dropwise). To the mixture was added 200 mL EtOAc and the reactionwas filtered through a bed of celite and celite washed with 200 mLEtOAc. The layers were separated and the aqueous layer acidified withtrifluoroacetic acid (74 g) to pH=1 and stirred overnight. A smallamount of solids precipitated over that time. The aqueous layer wasextracted with EtOAc, (3×100 mL) and the combinedorganic layers werewashed with 100 mL sat'd NaCl, dried over MgSO4, and concentrated invacuo to give 90 g of a crude yellow oil This oil was purified by columnchromatography: silica gel, ¼ EtOAc/Hexanes (R_(f) 0.4) to obtain 15.4 g(92%) of the desired product as a pale orange oil (87% pure by GC). Theproduct was further purified by vacuum distillation to obtain thedesired product as a colorless liquid; BP 50-53° C./0.4 mm Hg; ¹H NMR(500 MHz, CDCl3) δ 1.35 (s, 6H), 2.7 (m, 2H), 5.55 (m, 1H), 6.15 (m,1H); ¹³C NMR (125 MHz, CDCl3) δ 28.63, 41.43, 82.26, 122.62, 136.32,170.46; (97.8% by GC).

Example 7

The methylmethacrylate(MMA)/methacrylic acid(MAA)/dimethyltuliplin(DMMBL) (42.1/16.85/41.08 w/w/w) copolymer was prepared by charging thefollowing components to a 100 mL flask equipped with a thermocouple,stirrer, dropping funnel, reflux condenser and the means for bubblingnitrogen through the reaction. Parts by Weight Grams Portion 1 Methylmethacrylate (MMA) 0.8 Methacrylic acid (MAA) 0.32 Dimethyltuliplin(DMMBL) 0.78 Methylethyl ketone (MEK) 10.00 Portion 2 MEK 2.02,2′-Azobis (2,4-Dimethyl Valeronitrile): Vazo ®-52 0.08 Portion 3 MEK16.0 2,2′-Azobis (2,4-Dimethyl Valeronitrile): Vazo ®-52 0.96 Portion 4Methyl methacrylate (MMA) 7.20 Methacrylic acid (MAA) 2.88Dimethyltuliplin (DMMBL) 7.03 Total 48.05The monomers in portion 1 were dissolved in 10 grams of MEK in thereaction flask. Nitrogen was sparged through the solution in thereaction flask while heating the solution by a mantle to reach thesolution temperature to reflux. Portion 2, Vazo®-52 was dissolved in 2grams of MEK in a container and added into the reaction flask. Then thePortion 3, Vazo®-52 initiator solution and Portion 4 monomer mixturewere fed into the reaction flask at a uniform rate over 6 hours and 4hours respectively at the reflux temperature. After the initiator feedwas over, the polymerization was continued for another 1 hour at refluxtemperature. Finally the polymer was precipitated by adding the polymersolution into a large excess (500 grams) of petroleum ether andfiltered. The polymer was rinsed twice with a small amount of petroleumether, filteredand dried in a vacuum oven overnight at 25-30° C. Thepolymer yield was 13.58 grams (71.5%).

Example 8

The following solution was prepared and magnetically stirred overnight.Component Wt. (gm) MMA/MAA/DM-MBL copolymer 1.149 (weight feed ratio:42.1/16.9/41.0) as described in Example 7 Cyclohexanone 7.803 t-ButylLithocholate 0.300 6.82% (wt) solution of triphenylsulfonium nonaflate0.748 dissolved in cyclohexanone which had been filtered through a 0.45μPTFE syringe filter.

Spin coating was done using a Brewer Science Inc. Model-100CBcombination spin coater/hotplate on a 4 in. diameter Type “P”, <100>orientation, silicon wafer. Development was performed by hand dipping ina dish.

The wafer was prepared by depositing 6 mL of hexamethyldisilazane (HMDS)primer and spinning at 5000 rpm for 10 seconds. Then about 3 mL of theabove solution, after filtering through a 0.45 μm PTFE syringe filter,were deposited and spun at 3000 rpm for 60 seconds, and baked at 120° C.for 60 seconds. 248 nm imaging was accomplished by exposing the coatedwafer to light obtained by passing broadband UV light from an ORIELModel-82421 Solar Simulator (1000 watt) through a 248 nm interferencefilter which passes about 30% of the energy at 248 nm. Exposure time was30 seconds, providing an unaftenuated dose of 20.5 mJ/cm². By using amask with 18 positions of varying neutral optical density, a widevariety of exposure doses were generated. After exposure the exposedwafer was baked at 120° C. for 120 seconds.

The wafer was developed in aqueous tetramethylammonium hydroxide (TMAH)solution (OHKA NMD-3, 1.19% TMAH solution) for 30 sec to give a positiveimage.

1. A photoresist composition comprising: (a)a protected materialcomprising a protecting group which is: A. a cyclic ether group havingthe structure I or II:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout 8; wherein the protected material is substantially free of an acidgroup with a pKa of <11; or B. a cyclic ester having structure III:

wherein R₁ and R₂ independently represent a substituted or anunsubstituted straight chain or branched chain alkyl group, aromaticgroup, aralkyl, or alkaryl group, n is an integer of 1 to about 4; and(b) a photoactive component.
 2. The photoresist composition of claim 1wherein the cyclic ether protecting group has the structure:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout
 8. 3. The photoresist composition of claim 2 wherein R_(f) andR_(f)′ are each perfluoroalkyl groups of 1 to 5 carbon atoms, p is zeroand R is a hydrogen atom.
 4. The photoresist composition of claim 3wherein R_(f) and R_(f)′ are each CF₃.
 5. The photoresist composition ofclaim 1 wherein in the cyclic ester B, of structure III, n is 1 and R₁and R₂ are each CH₃, and at least one point of attachment of the cyclicester to the protected material is through the following positions onstructure III: a saturated ring carbon, R₁ or R₂.
 6. The photoresistcomposition of claim 1 wherein the protected material is a polymericbinder.
 7. The photoresist composition of claim 6 wherein the polymericbinder has an absorption coefficient of less than about 4.0 μm⁻¹ at awavelength of about 157 nm.
 8. The photoresist composition of claim 6wherein the cyclic ester group B is incorporated by copolymerizationwith γ,γ-dimethyl-α-methylene-γ-butyrolactone.
 9. The photoresistcomposition of claim 1 wherein the protected material is a dissolutioninhibitor.
 10. The photoresist composition of claim 9 wherein thedissolution inhibitor comprises a paraffinic, cycloparaffinic oroligomeric compound containing at least one cyclic ether protectinggroup A of structures I or II

wherein R_(f) and R_(f)′ independently represent fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF2)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout 8; wherein the protected material is substantially free of an acidgroup with a pKa of <11.
 11. The photoresist composition of claim 9wherein the dissolution inhibitor comprises a paraffinic,cycloparaffinic or oligomeric compound containing at least one cyclicester protecting group of the structure III

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; asubstituted straight chain or branched chain alkyl group, aromaticgroup, aralkyl or alkaryl containing at least one heteroatom selectedfrom the group consisting of O, S, N, P and halogen; and n is an integerranging from 1 to about
 4. 12. The photoresist composition of claim 9wherein the dissolution inhibitor has an absorption of less than about4.0 μm⁻¹ at a wavelength of about 157 nm.
 13. A process for preparing aphotoresist image on a substrate comprising, in order:
 1. forming aphotoresist layer on a substrate, wherein the photoresist layer isprepared from a photoresist composition comprises: (a) a protectedmaterial comprising a protecting group which is: A. a cyclic ether grouphaving structure I

or II: wherein R_(f) and R_(f)′ are the same or different fluoroalkylgroups of from one to about ten carbon atoms or taken together are(CF₂)_(a) wherein a is an integer ranging from 2 to about 10, Rindependently represents a hydrogen atom or a straight chain or branchedchain alkyl group of 1 to about 10 carbon atoms, and p is an integer offrom 0 to about 8; wherein the protected material is substantially freeof an acid group with a pKa of <11; or B. a cyclic ester havingstructure III:

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about 4; and (b) aphotoactive component;
 2. imagewise exposing the photoresist layer toform imaged and non-imaged areas; and
 3. developing the exposedphotoresist layer having imaged and non-imaged areas to form the reliefimage on the substrate.
 14. The process of claim 13 wherein theprotecting group comprises a cyclic ether group having the structure:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout
 8. 15. The process of claim 13 wherein the protecting group is acyclic ester group having the structure III:

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about
 4. 16. The process ofclaim 13 wherein the protected material is a polymeric binder.
 17. Theprocess of claim 16 wherein the polymeric binder has an absorption ofless than about 4.0 μm⁻¹ at a wavelength of about 157 nm.
 18. Theprocess of claim 15 wherein the cyclic ester group B is derived frompolymerization with γ,γ-dimethyl-α-methylene-γ-butyrolactone.
 19. Theprocess of claim 13 wherein the protected material is a dissolutioninhibitor.
 20. The process of claim 19 wherein the dissolution inhibitorcomprises a paraffinic, cycloparaffinic or oligomeric compoundcontaining at least one cyclic ether functional groups having thestructure:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout
 8. 21. The process of claim 20 wherein the protected material is adissolution inhibitor comprising a paraffinic, cycloparaffinic oroligomeric compound containing at least one cyclic ester functionalgroups having the structure:

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about
 4. 22. The process ofclaim 20 wherein the dissolution inhibitor has an absorption of lessthan about 4.0 μm⁻¹ at a wavelength of about 157 nm.
 23. The photoresistcomposition of claim 1 in which in structure III the at least one pointof attachment to the protected material is through a saturated ringcarbon, R₁ or R₂, of the cyclic ester.
 24. The photoresist compositionof claim 1 further comprising a solvent.
 25. The process of claim 13 inwhich in structure III the at least one point of attachment to theprotected material is through a saturated ring carbon, R₁ or R₂, of thecyclic ester.
 26. A coated substrate for semiconductor manufacturecomprising a substrate having on a surface thereof a coating of thephotoresist composition of any one of claims 1 to 12, 23 and
 24. 27. Thecoated substrate of claim 26 wherein the substrate comprises silicon,silicon oxide or silicon nitride.
 28. The coated substrate of claim 26wherein the substrate is primed.
 29. The coated substrate of claim 28wherein the substrate is primed with hexamethyldisilazane.
 30. Thecoated substrate of claim 26 wherein the photoresist composition iscoated onto the surface of the substrate by spin coating.